A dispenser which has given excellent results is that of the present Applicant described and protected in international patent application PCT/EP 02/11765. This dispenser has a support means comprising, for containing the active substance, a reservoir located in a position subjected to the action of the flushing water flow and arranged to receive the mouth of the bottle and, foreclosing the mouth of the bottle, a closure member positioned in said containing reservoir and with which there is associated at least one passage means for the active substance to enable the active substance to pass from the internal chamber of the bottle to the containing reservoir; said containing reservoir defines a volume for containing a quantity of active substance which closes said passage means for the active substance. The containing reservoir has an upwardly facing concavity arranged to contain a determined level of liquid, and to contain the bottle exit mouth with its lower passage cross-section positioned below the maximum level of the liquid present in the reservoir.
For each flush, the flushing water penetrates into the containing reservoir and carries away a small quantity of the active substance contained in the reservoir, to dilute it and release its deodorant/cleansing/refreshing/disinfectant action. When a part of the active substance is carried away, this, probably together with the turbulence produced by the flush, causes a little ventilation air to enter the bottle, to cause a gauged descent of the active substance, corresponding to one measure, with consequent restoration of the level in the reservoir.
This type of dispenser has been shown to have a relatively long life, with a behaviour which is constant both with time and for different shapes of the W.C. reservoir; moreover the active substance contained in the bottle maintains its active characteristics (deodorant/cleansing/refreshing/disinfectant and the like) constant or nearly constant with time, for a relatively large number of flushes (up to 250–450 flushes with 50–55 ml of active substance), and does not mix with the water other than to a relatively small extent and only at the end of its life.
Dispensers are also known having a single support for supporting two bottles in an inverted position, with their mouth facing downwards in a position subjected to the action of the flushing water flow, these bottles being separate from the support means and having separate internal chambers, each or containing an active substance in the liquid state. Examples of these dispensers are illustrated in the documents WO-A-02/40792 and WO-A-02/40787. An advantage of these dispensers is that substances which cannot be combined with each other can be used at the same time, as is the case if in addition to a purifying and perfuming substance, a substance for preventing lime scale formation and/or a bleaching solution are also to be used, these latter being often non-combinable with the former.
It has been found that if the dispenser of patent application PCT/EP 02/11765 is modified to comprise two (or more) mutually independent bottles and a like number of containing reservoirs for the active substance, located in positions subject to the action of the flushing water flow to receive the mouth of a respective bottle, the dispenser when in use manifests a considerable and virtually unacceptable difference in its behaviour and in particular in the consumption of the two liquids, so that one empties before the other.